intelligence believes chemical weapons have been used, but he seemed to issue the assad regime a warning. >> we have to make sure that we know exactly what happened, what was the nature of the incident, what can we document, what can we prove. so i have instructed my teams to work closely with all other countries in the region and international organizations and institutions to find out precisely whether or not this red line was crossed. once we establish the facts, i have made clear that the use of chemical weapons is a game-changer. >> reporter: so, chris, the big takeaway of this trip if it ended today is this, the united states and israel are more on the same diplomatic page than ever before on iran. when iran would get nuclear weapons and what the response would be if there's proof that they're pursuing them. two, we're a long ways away from even getting middle east peace negotiations in the talking phase, but there's optimism that at least there may be an attempt to have everybody agree, okay, no preconditions and everybody will sit down. and then of course you heard that syria thr